Washing machine

ABSTRACT

A washing machine includes an outer tub, and a counterweight fastened to the outer tub by a screwed connection. The screwed connection includes a screw guided through an opening of the counterweight, a spiked plate at an end of the screw with a spike-type projection in a fastening section of the outer tub that non-rotatably secures the spiked plate, and a brace at the other end of the screw that braces the counterweight and the fastening section with the spiked plate.

The invention relates to a washing machine according to the preamble of claim 1.

To support a balanced washing operation of the washing machine, the outer tub of the washing machine inside which the washing drum rotates is fitted with counterweights. These may be fastened to the outer tub by means of screwed connections.

A screwed connection for fastening a counterweight to an outer tub of a washing machine is known from US 2005/005650 A1. The screwed connection has, when assembled, a screw guided through the counterweight, the screw being screwed into a receiving thread of the outer tub. The screw head abuts against an abutment surface of the counterweight, the abutment surface facing away from the outer tub.

A further screwed connection for fastening the counterweight to the outer tub is known from DE 42 38 685 A1, in which, when assembled, the screw head abuts via a washer configured as a spring plate against the abutment surface of the counterweight facing away from the outer tub. The screw head is screwed into a screw boss configured in a same material and in one piece with the outer tub. The screw boss projects through an assembly hole into the counterweight.

To secure the screwed connection between the counterweight and the outer tub non-rotatably, it is known for a screw to be used, between the screw head and the screw shaft of which an approximately rectangular securing collar is provided. The securing collar of the screw is inserted into a corresponding through opening of a securing plate which is in turn arranged non-rotatably relative to the counterweight. To prevent rotation, a special screw, configured with the securing collar, and a securing plate are therefore required. The outlay in terms of assembly and components to secure the screw non-rotatably is therefore correspondingly large.

The object of the invention is to provide a washing machine in which the counterweight is fastened to the outer tub with a reduced number of components.

The object is achieved in a washing machine having the features of claim 1. Advantageous further developments of the invention are disclosed in the subclaims which are supported in the description below and in the drawings.

According to the characterizing clause of claim 1, at least one of the bracing elements at the ends is configured as a spiked plate having at least one spike-type projection. When the counterweight is fastened, the spike-type projection is forced in the direction of bracing into the fastening section of the outer tub and the spiked plate is thereby non-rotatably secured. An additional securing plate with associated securing collar of the screw, as used in the prior art, can thus, for the purposes of simplifying assembly and reducing the number of components, be dispensed with. Preferably, a multiplicity of spike-type projections is provided.

The two bracing elements at the ends can for the purposes of the invention be a threaded nut and/or a screw head. The bracing element can optionally also be a washer which is forced by means of the threaded nut or the screw head against the fastening section of the outer tub.

The spiked plate according to the invention can preferably be configured as a spiked nut which can be screwed together with the screw element. Irrespective of the screw used, the spiked nut is adapted according to the invention, whereas the screw can be configured conventionally, with no additional rotation-preventing elements.

The spiked plate can be a deep-drawn sheet metal part made, for example, of a spring-hardened stainless steel sheet, as a result of which the spiked plate is, in production engineering terms, easy to produce.

Alternatively, the spiked plate can also be configured as a screw head of the screw element. Here, the spike-type projections of the screw head point in the direction of the threaded shaft of the screw element. The screw serves a dual function here: both for bracing and for non-rotatably securing the screwed connection. The spike-type projections here are arranged on the underside of the screw head facing toward the outer-tub fastening section.

As a further alternative, the spiked plate can also be a washer which is associated with the screw head of the screw element. The washer is configured such that it is non-rotatably connected to the screw head. For such a non-rotatable connection the washer can have a recess, the inner contour of which is adapted to the outer contour of the screw head (e.g. a hexagonal inner contour). When fastened, the screw head engages in a form-locking manner with the inner contour of the recess of the washer, as a result of which the screw cannot rotate relative to the washer.

To simplify assembly, the at least one spike-type projection of the spiked plate can have a rounded spike tip, which, when the screwed connection has not yet been tightened prior to assembly, can give rise to the following advantages: prior to assembly, the spiked plate with its spike-type projection still abuts loosely against the outer-tub fastening section. Because the tip of the spike-type projection is rounded, the spiked plate can readily be displaced along the fastening section. Such a displacement would, in the case of an angular or sharply pointed spike tip, lead to the spike-type projection “catching” in the fastening section and consequently to a stiff sliding motion.

The spiked plate can preferably have a polygonal peripheral profile with an even number of sides. This can facilitate the application of a tool to the spiked plate. The spiked plate can, for the sake of further simplicity, have at least one pair of parallel opposing lateral surfaces. The lateral surfaces of the spiked plate serve a duel function: as a tool application and as lateral stops to further secure the spiked plate non-rotatably. For such additional rotation prevention, the spiked plate according to the invention can be associated with at least one rotation stop configured on the fastening section, which, besides the at least one spike-type projection of the spiked plate, ensures that the screwed connection is non-rotatably secure. To this end, the rotation stop configured on the fastening section can have two parallel opposite side walls.

The spiked plate with its lateral stop surfaces can then be non-rotatably arranged between these side walls.

To increase the functionality of the spiked plate, the latter can have an inner screw-element fastening section and an outer plate-shaped abutment section which abuts under pressure against the outer-tub fastening section. The at least one spike-type projection is provided on the plate-shaped abutment section. When the counterweight is fastened, the inner screw-element fastening section engages rigidly with the screw. In a special embodiment, the screw-element fastening section can be a receiving thread into which the screw is screwed.

For a permanently reliable fastening of the counterweight to the outer tub, it is preferable for an additional pretensioning element to be associated with the screwed connection. The pretensioning element permanently maintains a pretension between the bracing elements and the counterweight and/or the outer-tub fastening section, including also in the event of strong dynamic stresses on the screwed connection caused by operation of the washing machine and in the event of retardations and plastic or entropy-plastic deformations, as can occur under long-term stressing, particularly of an outer-tub fastening section made of plastic and/or other (plastic) parts directly associated with the screwed connection.

The pretensioning element may according to the invention be integrated in the spiked plate. The pretensioning element is advantageously a plate-type spring section, which is provided between the inner screw-element fastening section and the outer plate-shaped abutment section of the spiked plate. The plate-type spring section can be configured as a section of a cone. Where the spiked plate is configured as a spiked nut, a receiving thread for the screw element can be provided in the inner screw-element fastening section. The receiving thread can be provided in a central base region of the spiked plate. Alternatively, the inner screw-element fastening section can have a threaded sleeve on the inside of which the receiving thread is provided.

The threaded sleeve can here be provided on the side of the spiked plate facing away from the spike-type projections. Likewise, the threaded sleeve can also be provided on the side of the spiked plate facing toward the spike-type projections. Where the length is appropriate, the threaded sleeve here can, together with the threaded shaft, be guided through the fastening section of the outer tub. The threaded shaft of the screw does not therefore come directly into contact with the outer-tub fastening section, but only the smooth exterior of the threaded sleeve of the spiked plate.

Where the spiked plate is configured as a screw head, the inner screw-element fastening section can also be non-rotatably connected, in particular integrally connected, to the screw element.

The outer-tub fastening section can have a laterally open insertion slot, through which the screw element projects. Where the bracing elements are screwed loosely, one of the bracing elements can therefore be inserted into the laterally open insertion slot and displaced therein to a predetermined definitive fastening position. The fastening section of the outer tub can, in addition, form a guide channel. The insertion slot can open into this guide channel and extend in the longitudinal direction of same. When the screwed connection is assembled, the spiked plate can then be displaced along the guide channel and the screw element along the insertion slot to a definitive fastening position.

The fastening section is preferably configured together with the outer tub in the same material and in one piece. The outer tub and/or the fastening section can in production engineering terms advantageously be made of plastic. In a method for fastening the counterweight to the outer tub, a screw of the screwed connection according to the invention can firstly be guided through the counterweight. The end of the screw guided through the counterweight can then loosely be screwed to a bracing element at the end. The bracing element at the end is the spiked plate according to the invention. The loosely screwed bracing element at the end can then be inserted into the guide channel of the outer-tub fastening section. The counterweight can then, to adjust position, be displaced with the loosely screwed bracing element along the guide channel; and when the arrangement of the counterweight is correct, the screwed connection can be tightened in its definitive fastening position.

Five exemplary embodiments of the invention will be described below with the aid of the attached drawings, in which:

FIG. 1 shows according to the first exemplary embodiment, in a schematic partial view, an upper counterweight which is fastened by means of screwed connections to the outer tub of the washing machine;

FIG. 2 shows, in an enlarged sectional representation, one of the screwed connections between the counterweight and the outer tub;

FIG. 3 shows, in a perspective representation, a threaded nut used for the screwed connection;

FIG. 4 shows a spiked plate embodied as a threaded nut, according to the second exemplary embodiment;

FIG. 5 shows a spiked plate embodied as a threaded nut, according to the third exemplary embodiment;

FIG. 6 shows a spiked plate embodied as a screw head, according to the fourth exemplary embodiment; and

FIG. 7 shows a spiked plate embodied as a washer, according to the fifth exemplary embodiment.

FIG. 1 shows in a schematic side view a partial area of an outer tub 1 of a washing machine and a counterweight 3 fastened to the top of the outer tub 1, which counterweight ensures a balanced washing operation. The elongately configured counterweight 3 extends transversely relative to a central axis (not shown) of the hollow cylindrical outer tub 1 and lies at its two opposing ends on hollow support profiles 5 of the outer tub 1. The counterweight 3 is mounted at each of its longitudinal ends on the associated hollow support profile 5 of the outer tub 1 by means of a screwed connection 7.

The counterweight 3 is produced in a known manner from a cast material, for example cast iron or concrete, or another suitable material. The outer tub 1 is an injection-molded plastic part. The hollow support profile 5 is molded integrally onto the outer tub 1 in an easy-to-manufacture manner.

FIG. 2 shows one of the screwed connections 7 from FIG. 1 in an enlarged partial sectional view. The opposite screwed connection (not shown) is configured identically.

As can be seen from FIG. 2, the screwed connection 7 is configured in three parts, with a screw 9 or screw element, a washer 11 and a spiked plate 13 embodied as a threaded nut. The screwed connection 7 is shown in FIG. 2 with the counterweight 3 and the outer tub 1 in the assembled position. The screw 9 is guided with its threaded shaft 15 through an assembly hole 17 of the counterweight 3. Here, the screw head 19 is supported via the washer 11 on an abutment surface 21 of the counterweight 3 facing away from the outer tub 1. The abutment surface 21 here is the base of a conically extended countersunk hole 23.

The threaded shaft 15 guided through the assembly hole 17 projects with its shaft end into an insertion channel 25 of the hollow support profile 5. The insertion channel 25 extends perpendicular to the plane of the drawing of FIG. 2 and is delimited by two side walls 27 and by an upper covering wall 29 connecting the two side walls 27.

In the present exemplary embodiment, the upper covering wall 29 is a fastening section of the outer tub 1. This fastening section 29 and the counterweight 3 are braced according to FIGS. 1 and 2 between the screw head 19 and the spiked plate 13 which are the bracing elements at the ends of the screwed connection 7. A narrow insertion slot 31 which extends along the guide channel 25 and through which the threaded shaft 15 projects, is provided in the covering wall 29 for this purpose. The insertion slot 31 is laterally open and opens into the guide channel 25

The spiked plate 13 embodied as a threaded nut is screwed inside the guide channel 25 to the (in FIG. 2) lower end of the threaded shaft 15. The spiked plate 13 thus engages behind the covering wall 29. In the assembled position shown, the counterweight 2 and the covering wall 29 of the outer tub 1 are thus braced between the screw head 19 and the spiked plate 13.

The spiked plate 13 embodied as a threaded nut is shown in detail in FIG. 3 in an enlarged perspective view. The threaded nut 13 is made of a spring-hardened stainless steel sheet with a material thickness of c. 1 mm. The spiked plate 13 has according to FIG. 3 an inner screw-element fastening section 32. The inner screw-element fastening section 32 is fitted here with an internal thread 33 with which the end of the shaft 15 of the screw 9 can be screwed together.

As can further be seen from FIG. 3, the screw-element fastening section 32 of the spiked plate 13 has a centrally arranged threaded sleeve 35 in which the internal thread 33 is provided. Connected to the threaded sleeve 35 in the direction of the outer contour of the spiked plate 13 is a conical section which forms a plate-type spring section 37 (in the manner of a plate spring). On its outer edge region, the spring section 37 merges integrally into a plate-shaped, flat abutment section 39, extending in the radial direction of the spiked plate 13. The abutment section 39 has a uniform octagonal outer contour with opposite pairs of sides or stop surfaces 41 respectively running parallel to one another. When assembled, the spiked plate 13 presses with the lower (in FIG. 3) surface of the abutment section 39 against the covering wall 29.

A permanently non-rotatable seating of the spiked plate 13 embodied as a threaded nut is for operating safety of great importance. According to the invention, projections 43 with rounded spike tips are therefore provided on the side of the spiked plate 13 facing the covering wall 29. The spike-type projections 43 are provided on the side of the spiked plate 13 facing away from the threaded sleeve 35 and extend in a direction parallel or substantially parallel to the longitudinal direction of the threaded shaft 15. When the counterweight 3 is fastened, the spike-type projections 43 are pressed by the clamping forces of the screwed connection in the direction of bracing into the plastic material of the covering wall 29.

For additional rotation security to prevent a rotational movement of the spiked plate 13, the distance b shown in FIG. 3 between two opposing lateral stop surfaces 41 is dimensioned such that each of the opposing stop surfaces 41 lies with limited play c opposite the facing side wall 27 of the outer-tub hollow support profile 5 (see FIG. 2). The two side walls 27 of the hollow support profile 5 therefore act as a rotation stop, which additionally limits a rotational movement of the spiked plate 13.

To fasten the counterweight 3 to the outer tub 1, the screw 9 is firstly guided from the side of the counterweight 3 facing away from the outer tub 1 through the assembly opening 17. The spiked plate 13 is then loosely screwed to the lower end of the shaft 15 in FIG. 2. This loose screwed connection can be effected still independently of the outer tub 1. To connect the counterweight 3 to the outer tub 1, the spiked plate 13 which is loosely connected with the screw 9 is then inserted into the laterally open guide channel 25 of the outer tub 1. The threaded shaft 15 of the screw 9 now projects through the insertion slot 31, while the covering wall 29 is arranged between the threaded nut 13 and the counterweight 3. In this condition, the loosely screwed spiked plate 13 can be displaced along the guide channel 25 and the screw 9 along the insertion slot 31 to a correct or definitive fastening position.

After correct positioning of the counterweight 3 has been carried out, the screwed connection 7 is tightened by means of a tool applied to the screw head 19.

To simplify the tightening process, the spiked plate 13 is non-rotatably held by means of its lateral stop surfaces 41 between the two side walls 27. On the other hand, the play c provided between the stop surfaces 41 of the spiked plate 13 and the side walls 27, and the rounded projections 43 ensure that, when the spiked plate 13 is loosely screwed on, the spiked plate 13 can be displaced smoothly inside the guide channel 25.

FIG. 4 shows the spiked plate 13 according to the second exemplary embodiment. The basic structure and mode of operation of the spiked plate 13 shown in FIG. 4 corresponds to the structure and mode of operation of the spiked plate 13 of the first exemplary embodiment as shown in FIGS. 1 to 3, so corresponding reference characters are used for features that work the same, and the description below describes, in particular, the differences in relation to the first exemplary embodiment.

Accordingly, the receiving thread 33 for the screw 9 is likewise provided in the inner screw-element fastening section 32 of the spiked plate 13. In contrast to the first exemplary embodiment, however, the receiving thread 33 is not provided inside the threaded sleeve 35 but rather in a central base region 45. The central base region 45 merges via the plate-type spring section 37 into the outer plate-shaped abutment region 39 of the spiked plate. On the (in the representation according to FIG. 4) top side of the abutment region 39, the rounded spike-type projections 43 are again provided.

FIG. 5 shows the spiked plate 13 according to the third exemplary embodiment. The spiked plate shown in FIG. 5 has—as in the first exemplary embodiment—a central threaded sleeve 35, connected to the (in FIG. 5) lower end region of which is the plate-type spring section 37, which merges into the outer plate-shaped abutment section 39.

In contrast to the first exemplary embodiment, however, the threaded sleeve 35 is not provided on the side of the spiked plate 13 facing away from the spike-type projections 43, but rather on the side facing toward the spike-type projections 43. Viewed in the axial direction of the spiked plate 13, indicated in FIG. 5 by a dot-dash line, the central threaded sleeve 33, the spring section 37 and the radially outer abutment section 39 are therefore partially “nested”, as a result of which the overall height of the spiked plate 13 is reduced in comparison to the first exemplary embodiment. This spiked plate 13 is therefore particularly suitable for a very shallow guide channel.

With an appropriate length, the threaded sleeve 35 is guided together with the threaded shaft 15 screwed therein through the insertion slot 31 of the covering wall 29 of the hollow support profile 5. The edges of the insertion slot 31 are not therefore directly in contact with the threaded shaft 15 of the screw 9. Rather, the smooth outside of the threaded sleeve 35 advantageously comes into contact with the edges of the insertion slot, as a result of which the threaded shaft 15 is displaced smoothly inside the insertion slot 31.

FIG. 6 shows the spiked plate 13 according to the fourth exemplary embodiment. In contrast to the first three exemplary embodiments, here the spiked plate 13 is integrally configured with the screw 9 as the screw head thereof. The spiked plate 13 consequently has a central head section 47. Radially outwardly adjacent to the central head section 47 is the plate-type spring section 37 which merges into the abutment section 39. In the exploded view shown, a conventional washer 11 and a conventional threaded nut 49 are associated with the screw 9, it being possible for said threaded nut to be screwed together with the (in FIG. 6) upper end of the shaft 15 so as to brace the covering wall 29 and the counterweight 3. When the counterweight 3 is fastened, the threaded nut 49 with its washer 11 is supported in the variant according to FIG. 6 on the abutment surface 21 of the counterweight 3 facing away from the outer tub 1, as shown in FIG. 2. In a corresponding manner, the spiked plate configured as a screw head is arranged inside the guide channel 25 of the hollow support profile 5.

FIG. 7 shows the screwed connection 7 according to the fifth exemplary embodiment, likewise in an exploded view. As can be seen from FIG. 7, the spiked plate 13 is configured here as a washer of the screw head 19. The spiked plate 13 here has a central recess 51, the inner contour of which fits in a form-locking manner with the outer contour of the screw head 19. Adjacent to the central recess 51 is the plate-type spring section 37 which again merges into the radially extending plate-shaped abutment section 39. Arranged in turn on the abutment section 39 are the spike-type projections 43. The end of the shaft 15, which is fashioned with a thread, of the screw 9 is likewise screwed to a conventional threaded nut 49. When the counterweight 3 is fastened, the spiked plate 13 is arranged, together with the screw head 19 arranged in its recess 51, in the guide channel 25. Here, the spiked plate 13 sits non-rotatably on the covering wall 29 with its projections 43 pressed into the plastic material of the covering wall 13. Consequently, due to the form-locking connection between the outer contour of the screw head 19 and the inner contour of the recess 51, the screw head 19 is non-rotatably connected to the spiked plate.

Reference characters in the claims, the description and the drawings serve merely to provide a better understanding of the invention and are not intended to limit the scope of protection.

LIST OF REFERENCE CHARACTERS

-   1 outer tub -   3 counterweight -   5 hollow support profile -   7 screwed connection -   9 screw/screw element -   11 washer -   13 spiked plate -   15 shaft/threaded shaft -   17 assembly hole -   19 screw head -   21 abutment surface -   23 countersunk hole -   25 insertion channel/guide channel -   27 side walls -   29 covering wall/fastening section -   31 insertion slot 31 -   32 screw-element fastening section of 13 -   33 internal thread -   35 threaded sleeve -   37 plate-type spring section -   39 abutment section -   41 stop surfaces -   43 spike-type projections of 13 -   45 base region -   47 head section -   49 threaded nut -   51 recess -   a material thickness -   b distance -   c play between 27 and 41 

1-17. (canceled)
 18. A washing machine comprising: an outer tub; and a counterweight fastened to the outer tub by a screwed connection comprising: a screw guided through an opening of the counterweight, a spiked plate at an end of the screw with a spike-type projection in a fastening section of the outer tub that non-rotatably secures the spiked plate, and a brace at the other end of the screw that braces the counterweight and the fastening section with the spiked plate.
 19. The washing machine of claim 18, wherein the spiked plate comprises a spiked nut which can be screwed with the screw.
 20. The washing machine of claim 18, wherein the spiked plate comprises a screw head of the screw.
 21. The washing machine of claim 18, wherein the spiked plate comprises a washer associated with a screw head of the screw element, by means of which washer the screw head can be non-rotatably connected.
 22. The washing machine of claim 18, wherein the spike-type projection has a rounded spike tip.
 23. The washing machine of claim 18, wherein the spiked plate has a polygonal peripheral profile with an even number of edges.
 24. The washing machine of claim 18, wherein the spiked plate has a pair of parallel lateral surfaces.
 25. The washing machine of claim 18, further comprising a rotation stop on the fastening section associated with the spiked plate, which rotation stop forms an additional rotation prevention for the spiked plate.
 26. The washing machine of claim 25, wherein the rotation stop on the fastening section has two opposing side walls, parallel with one another, between which the spiked plate is non-rotatably arranged.
 27. The washing machine of claim 18, wherein the spiked plate comprises an inner screw fastening section and an outer plate-shaped abutment section abutting against the fastening section, and wherein the spike-type projection is on the outer plate-shaped abutment section.
 28. The washing machine of claim 27, wherein the spiked plate further comprises a plate-type spring section is between the inner screw fastening section and the outer plate-shaped abutment section.
 29. The washing machine of claim 27, wherein the spiked plate comprises a spiked nut and a receiving thread for the screw in the inner screw fastening section.
 30. The washing machine of claim 27, wherein the spiked plate comprises a screw head, and wherein the inner screw fastening section is non-rotatably connected to the screw.
 31. The washing machine of claim 30, wherein the inner screw fastening section is integrally non-rotatably connected to the screw.
 32. The washing machine of claim 18, wherein the outer-tub fastening section has a laterally open insertion slot through which the screw projects.
 33. The washing machine as claimed in claim 32, wherein the fastening section forms a guide channel into which the insertion slot opens and extends in a longitudinal direction, and wherein the spike plate is displaceable along the guide channel and the screw is displaceable along the insertion slot to a defined fastening position.
 34. The washing machine of claim 18, wherein the fastening section comprises the same material and forms one piece with the outer tub.
 35. The washing machine of claim 18, wherein the outer tub and/or the fastening section comprise plastic. 